Green preparation method for granular plastic additives

Abstract

The present invention relates to a method for preparing a granular plastic additive comprising the steps of a) providing at least one additive solution which comprises a plastic additive and a solvent,b) optionally mixing the additive solutions,c) thin film evaporation of the additive solution to produce a concentrated additive,d) agitation of the concentrated additive under vacuum to produce a hot melt,e) mixing a molten carrier polymer with the concentrated additive during the extrusion, andf) cooling and forming the hot melt comprising the plastic additive and the carrier polymer to produce the granular plastic additive.The invention also relates to the granular plastic additive obtainable by the method.

1 . A method for preparing a granular plastic additive comprising the steps of
 a) providing at least one additive solution which comprises a plastic additive and a solvent,   b) optionally mixing the additive solutions,   c) thin film evaporating the additive solution to produce a concentrated additive,   d) agitating the concentrated additive under vacuum to produce a hot melt,   e) mixing a molten carrier polymer with the concentrated additive during the agitation, and   f) cooling and forming the hot melt comprising the plastic additive and the carrier polymer to produce the granular plastic additive.   
     
     
         2 . The method according to  claim 1 , wherein the agitating is performed by extrusion or kneading. 
     
     
         3 . The method according to  claim 1 , wherein the agitating is performed by a single-screw extruder, multi-screw extruder, or a kneader. 
     
     
         4 . The method according to  claim 1 , wherein the solvent concentration is reduced during the agitation under vacuum. 
     
     
         5 . The method according to  claim 1 , wherein, during the agitation, the solvent concentration is reduced to produce a hot melt which comprises less than 10.000 ppm of the solvent. 
     
     
         6 . The method according to  claim 1 , wherein the mixing of the molten carrier polymer is performed by extrusion of the carrier polymer and feeding it into the hot melt in step d). 
     
     
         7 . The method according to  claim 1 , wherein the carrier polymer is a polyolefin. 
     
     
         8 . The method according to  claim 1 , wherein the granular plastic additive comprises 1 to 25 wt % of the carrier polymer. 
     
     
         9 . The method according to  claim 1 , wherein the solvent comprises toluene, xylene, ethylbenzol, trimethylbenzene, isopropylbenzene, diisopropylbenzene, a water-insoluble organic ketone, or mixtures thereof. 
     
     
         10 . The method according to  claim 1 , wherein, during the thin film evaporation, the solvent concentration is reduced to produce the concentrated additive which comprises less than 10 wt % of the solvent. 
     
     
         11 . The method according to  claim 1 , wherein in step a) at least two additive solutions were provided and mixed in step b). 
     
     
         12 . The method according to  claim 1 , wherein the plastic additive comprises a light stabilizer, a UV stabilizer, or a mixture thereof. 
     
     
         13 . The method according to  claim 1 , wherein the plastic additive comprises the light stabilizer of the formula (I) 
       
         
           
           
               
               
           
         
         and optionally a light stabilizer selected from the sterically hindered amines. 
       
     
     
         14 . The method according to  claim 1 , wherein the forming is performed after cooling by comminution. 
     
     
         15 . A granular plastic additive obtainable by the method of  claim 1 . 
     
     
         16 . The granular plastic additive according to  claim 15 , wherein the solvent is xylene and the solvent concentration in the granular plastic additive is below 10.000 ppm. 
     
     
         17 . The method according to  claim 1 , wherein the forming is performed after cooling by milling.